1. Field of the Invention
The present invention relates to a pattern recognition apparatus for recognizing characters or patterns from handwritten information representing handwriting.
2. Related Background Art
As general processing methods used in such apparatus, for example an on-line character recognition apparatus, there are already known the feature point pattern matching method and the basic stroke method. Said feature point pattern matching method consists of extracting at least three feature points representing each stroke of handwriting from the up/down information and x, y-coordinates of the pen entered from a tablet, determining the similarity with standard patterns registered in a dictionary, and providing a pattern of highest similarity as the result of recognition. The similarity is defined by the reciprocal of the sum of distances between the corresponding feature points of the entered character and the standard pattern.
On the other hand, the basic stroke method consists of approximating the strokes constituting a character by a group of vectors quantized in eight directions, classifying said vectors into certain basic strokes, and recognizing a character from the combination of said basic strokes.
These methods have following advantages and disadvantages:
1) The feature point pattern matching method is resistant to deformation of patterns, but requires a long recognition time. A very long recognition time is required if the sequential order of handwriting of a character is not specified.
2) The basic stroke method requires a shorter recognition time, but is weak to deformations such as characters with a strong personal touch or continuedly written characters, or a change in the sequential order of writing.
The conventional character/pattern recognition apparatus, employing only one recognition method, has been associated with following drawbacks:
(1) In case of an erroneous recognition, the reentry of the same character results in the same erroneous recognition, because the manner of writing is same as before; and
(2) The apparatus is not convenient for use as it cannot necessarily meet the requirement of the user, for example giving emphasis on a shorter recognition time while the user agrees to enter handwriting in carefully written manner, or emphasis on acceptance for rougher handwriting even if the recognition time becomes longer.